"The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon," the international team of research wrote.

"Many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses."

Tropical forests
are considered to be the biologically richest areas on the planet.

In order to assess the state of the world's protected areas, the team considered data from 60 areas, based on "262 detailed interviews, focusing on veteran field biologists and environmental scientists, who averaged more than two decades of experience".

"It is not enough to [protect] interiors while ignoring surrounding landscapes, which are being rapidly deforested, degraded and over-hunted," they observed.

"A failure to limit inter-related internal and external threats could predispose reserves to ecological decay, including taxonomically and functionally array in species communities and an erosion of fundamental ecosystem processes."